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T H E O R E T I C A L A N D T E C H N I C A L M A N U A L F O R T H E B E N C H T O P B I O F U M E H O O D ( B T E )

T H E O R E T I C A L A N D T E C H N I C A L M A N U A L F O R
T H E B E N C H T O P B I O F U M E H O O D ( B T E )
















G E R M F R E E
Theoretical and Technical Manual for the
Benchtop Biofume Hood (B T E)
©
Germfree Laboratories Incorporated
11 Aviator Way Ormond Beach, FL 32174
Phone 800.888.5357 Fax 386.677.1114
www.germfree.com




Table of Contents
Introduction
1

Services
4

Installation
10

Test Mode
11

Environmental Testing
12

Operation
13

Performance Testing
14

Air Balance
15

Airflow Smoke Test
16

Working in the BTE
17

Some Biological Donts
19

Airflow Diagram
20


V E N T I N G
R E C O M M E N D A T I O N S
BTE 4SS
21
BTE 6SS
22
D I A G R A M S
3SS
23
4SS
24
6SS
25
Wiring
26

Parts List
27 G E R M F R E E
1
Introduction
uring the past few decades, there has been an increase in the use of
Class II Laminar Flow Biological Safety Cabinets. These units were
designed to contain low and moderate risk microorganisms, but did not
provide for non-particulate materials that could pass through the supply HEPA
filters. The Total Exhaust BENCHTOP BIOFUME HOOD differs from other
Class II Laminar Flow Biological Safety Cabinets in that no air recirculates in the
cabinet. Therefore, there is no possible buildup of any non-particulate material in
the work area. In contrast, within a hood in which air recirculates, non-particulate
matter passes through the HEPA supply filter into the work area. Thus, the
BENCHTOP BIOFUME HOOD can be used for one or any combination of the
following biohazards:

Carcinogens
Radioactive gases
Potentially infectious materials
Volatiles
Noxious fumes
Subliming particulates

Besides ease of operation, the BENCHTOP BIOFUME HOOD provides
personnel and environmental protection from the aforementioned potential
hazards, and concurrently, offers product protection against cross-contamination.

Tissue culture and other sophisticated techniques frequently require that a variety
of substances be used within the same hood at different times and, not
infrequently, at the same time.

The inward air velocity required by various governmental agencies to handle the
above classes of potentially hazardous materials has been reported as 100, 125 and
150 linear feet per minute (fpm). Because of the inability of available Class II
cabinets to provide complete protection, particularly from carcinogens and
D
2
radioactive gases, it was apparent that a new concept in Biohazard Cabinetry was
needed that would meet four basic requirements:


1.
The protection of personnel and the environment from


exposure to potentially contagious particulates such as



bacteria, viruses, parasites, fungi, etc..
2.
The protection of personnel and the environment from


noxious fumes, potential carcinogens and radioactive


materials, by totally exhausting air from the cabinet.
3.
The establishment of a work area bathed with laminar flow,
containment-free air for the protection of materials.
4.
The provision of free ingress and egress of the operators hands
through a partially open front.

These features have been incorporated in GERMFREEs BENCHTOP
BIOFUME HOOD. The BENCHTOP BIOFUME HOOD is a vertical
downflow, unidirectional, laminar flow unit that differs from other Class II units
because THERE IS NO RECIRCULATION OF AIR. All air is totally
exhausted. Technologists now can have a far greater sense of security knowing
that air passing over their hands and forearms is not contaminated.

The BENCHTOP BIOFUME HOOD has dual capabilities. It may be used as a
BIOFLOW CHAMBER when working with potentially contagious particulates
such as bacteria, viruses, fungi, parasites etc., and/or it may be used for chemical
carcinogens and radioactive materials, with the outstanding feature that the work
area is bathed with laminar flow sterile air. This degree of personnel, product and
environmental protection was not previously available for work with non-
particulate materials.

The BENCHTOP BIOFUME HOOD exceeds the requirements for a Class 100
chamber as described in Federal Standard No. 209. This Standard outlines air
cleanliness classes and certain other environmental conditions of air required for
achieving and maintaining clean environmental levels. Federal Standard Class 100
is that class where particles 0.5 micron or larger must not exceed a total count of
100 particulates per cubic foot.

Biomedical engineering and technology have introduced safeguards into the design
of laboratory equipment but these safeguards cannot prevent human error!
3
Danger to personnel from carelessness or improperly used equipment cannot be
over-emphasized. There is NO substitute for safe, proper technique.































4
Services
The BENCHTOP BIOFUME HOOD is shipped complete with the following
accessories: variable speed blower motor control for supply blower (BFA-5); dual
magnehelic gauges (BFA-14); metal diffuser below supply filter (BFA-15); and air
exhaust failure alarm system. To make this hood operational, it must be hooked
up to an exhaust fan and a venting system. The unit is provided with both supply
and exhaust HEPA filters.

To move the unit through narrow doors, the light housing can be detached by
removing four screws. Also, the viewing panel with the attached light housing can
be removed by sliding the split hinges to the left after raising the panel until it is
parallel to the floor. This reduces the width of the BIOFUME HOOD to 30
inches. An additional 3/4" clearance is required for the two clamps located below
the viewing panel.

All controls are front-mounted, allowing the unit to be placed side-by-side with
other laboratory equipment and flush against the wall. Do not place the unit
within an area of excessive air turbulence or one subjected to high traffic. Test the
selected area with cigarette or chemical smoke and observe the movement of air.

ELECTRICAL:
All electrical components, except the supply motor and pressure switch, are
mounted in the control panel affixed to the front of the hood. There are no
electrical components in the biologically contaminated air stream. A nine-foot
long power cord with a molded-grounded plug exits from the control panel on the
right hand side as you face the cabinet. Electrical requirements for the hood are
(one) 15 amp, 115-volt electrical outlet. Variations in line voltage may cause
changes in blower performance.

CONTROL PANEL:
Components located on the face of the control panel are as follows:




2 amp circuit breaker (light)




10 amp circuit breaker




Audible alarm




Pilot lights (2), red & green




Start button
5




Stop button




On-off rocker switches (2)




Switch top-main/bottom-fluorescent lights




Speed control for supply blower

The control panel can be removed by unscrewing the two acorn nuts located at
each end. All components are mounted directly on the removable control panel.
Located inside the control panel is the internal circuitry and the ballast for the
fluorescent lights. Please note: wires leading to the supply motor and pressure
switch are threaded into the control panel through grommets in the upper right
hand corner. Care should be taken when removing this panel that these wires are
not disconnected.

A three-piece stainless steel shroud is attached to the unit to conceal the supply
blower-motor, exhaust filter, etc. It is attached to the sides on the top with studs
and nuts. The front piece houses the Magnehelic gauges and is key locked to the
sides. This can be lifted off the unit for servicing once the control panel is
removed by raising it up and out.

MAGNEHELIC GAUGES
Magnehelic gauges measure differential pressures across the supply and exhaust
filter. This information is to help determine filter loading. Each filter has its own
gauge because of differential pressures and the possibility of differential loading.
They are marked SUPPLY and EXHAUST. The SUPPLY is connected to
the high-pressure side and usually reads greater than .50 inch. The EXHAUST
is connected to the low-pressure side and usually reads approximately .25 inch.
The connection on the exhaust gauge takes its reading from the contaminated air
stream. Disconnection of the exhaust should only be undertaken after the unit has
been decontaminated. Readings in the Magnehelic gauges vary with each
individual set of filters and therefore is not a finite number. It is recommended
that you take note of this setting once the hood has been initially certified and
monitor it (monthly readings are frequent enough for most applications).

VARIABLE SPEED MOTOR CONTROL
The variable speed motor control for the supply blower is located beneath t